It is known to compress bitmaps, for example using run-length and outline techniques, so that less space is required to store them and so that less time is required to transmit them at a particular transmission rate. However, compression and decompression take time and processing power. For example, the world-wide-web has generated a need to have a range of large banner fonts. These can be stored and transmitted as outlines, which are compact, but a significant amount of processing power is required to render or decompress them from this form.